Cluster routing and management requirements have been developed for all nodes in a Common Channel Signaling (CCS) network, using signaling system number (SS7). Existing cluster routing and management requirements have a limitation which disallows cluster routing from a node to any cluster to which the node has direct links. This limitation is illustrated by FIG. 1, which shows a network 10 including a plurality of signaling transfer points (STPs) 12-18 connected to each other and connected to members A-C of cluster 20.
According to this limitation, if the E-linkset between STP 12 and member A is deployed as shown, STP 12 is unable to perform cluster routing and management to the cluster, whereas if the E-linkset from STP 12 to member A is not deployed, STP 12 can perform cluster routing and management to cluster 20. Thus, even if only one cluster member is connected via an E-linkset to an STP, that STP must perform full point code routing to every member of the cluster. To perform full point code routing, the STP must have a complete route-set administered for each cluster member, which, depending on the implementation, requires the use of additional memory in the STP.
Thus, this limitation restricts the advantages associated with cluster routing and management from a node to cases when direct links (i.e. E-linksets, F-linksets) are not deployed to members of a cluster. It is expected, however, that E-links will be deployed with increasing frequency over the next few years and that cluster routing and management will be desirable in such situations. Therefore, it is necessary to expand the current cluster routing and management requirements to allow cluster routing and management to be performed, even when E-links are deployed utilizing cluster routing and management diversity according to the present invention.
The phrase "cluster routing and management diversity" as used herein refers to the case when a signaling point (SP) is simultaneously performing both cluster and full point code routing and management to members of the same cluster, and where the administered routes may or may not be the same for all members of the cluster. For purposes of this discussion, an SP is any node (i.e. STP, SPCS, etc.), and an end node is anything that is not an STP, such as a Stored Program Control System (SPCS). Cluster routing and management diversity is an extension of previous cluster routing and management requirements, which apply when an SP uses the same routing (i.e., the same route-set) for all members of a cluster, as might be the case when a STP routes messages to remote clusters.
In addition to the "direct link" motivation for developing such requirements, there are additional needs satisfied by the present invention. First, work is currently underway to develop requirements to support a feature in which an SPCS recognizes multiple point codes (PCs) as its own, in support of architectures where different routing would be required for different PCs, even if those PCs are in the same cluster. In that case, cluster routing and management diversity would support cluster routing to the majority of the cluster, and full point code routing to the individual members that require special routing. Second, this feature could be useful in a SPCS that has F-links deployed to another SPCS. This is due to current requirements which indicate that if one SPCS has direct connectivity to another, then both SPCSs perform full point code routing to every member of each other's cluster, which means that a complete route-set must be administered for each cluster member. Finally, there is industry interest in developing a feature that allows cluster routing in the presence of E-links. In order to ensure compatibility between vendor implementations, it is important to establish a common, generic model for this feature.